Radio communication is performed among a plurality of radio communication devices. A frequency band is allocated to each radio communication service to perform the radio communication. However, at the present time, the number of radio communication services increases. As a result, it becomes difficult to allocate a different frequency band to a new radio communication service or a new radio communication application. That is, the radio communication services are in a saturation state.
As such, although the radio communication services are in a saturation state currently, it is known that there are frequency bands that are rarely used. This shows that a radio spectrum is not efficiently used.
Therefore, in order to promote efficient use of the radio spectrum, Federal Communication Commission (FCC) released a paper that proposed to allow an unlicensed radio communication service to have access to a non-used frequency band in 2002. The paper is prepared by Spectrum Policy Task Force (SPTF). An example of the radio communication that is improved according to this scenario is cognitive radio communication (for example, refer to Patent Document 1).
In a cognitive radio communication system, a process for establishing data communication (communication link) is executed. Specifically, first, spectrum sensing is performed over a special radio frequency range. Subsequently, a spectrum use situation is analyzed on the basis of the result of the spectrum sensing. Information is exchanged among components (nodes) constituting the cognitive radio communication system. The exchanged information includes sensing information and sensing control information. In this case, the nodes can perform sensing to generate sensing information or can acquire the sensing information from the other nodes. In this way, each node shares the sensing information with the other nodes. Accordingly, a sensing quality is improved. Then, in the cognitive radio communication system, a frequency band that is used for data communication is determined. Accordingly, the data communication can be performed.
However, each node of the cognitive radio communication system may not grasp a channel to be used for data communication, until the sensing is performed. Therefore, each node may not grasp a channel that is used to share the sensing information or the sensing control information.